Written Evidence submitted by Lorna Anguilano and Uche Onwukwe (SH0017)

Executive Summary

• Centuries of industrial use of the land in the UK has left a vast portion of the country struggling with issues of contamination with large remediation costs and socio-economic degradation of the area
• In parallel, anthropic use of the land continuously increase the amount of pollution in urban environments;
• Green solutions to sustain the soil decontamination and support the increase in nutrients in farming soils need to be investigated and trialled to ensure a more sustainable long term soil regeneration in the country with an improved food productivity and decrease in dependence from other countries for food import;

This submission addresses the following question:

What does UK Government need to do to tackle other stressors on soil health such as soil contamination?

1. What does UK Government need to do to tackle other stressors on soil health such as soil contamination?

1.1.1         The issue of soil contamination

1.1.2         Industrial use and soil contamination legacy

• The industrial use of the British land of the past centuries have left its mark leaving more than 200,000 sites identifiable as contaminated [1] . The contamination varies from high metal concentration in mining areas such as Yorkshire (the Barnsley Main heritage site for example contains for instance 5200ppm of titanium, 1550ppm of manganese and 1030ppm of zinc),
• The rural soil in the UK contains 369, 612 and 81ppms of titanium, manganese and zinc respectively, indicating a contamination of 10 times the amount of healthy soils).
• These issues of high metal contaminants are not visible only on heritage sites but also in residential areas which had different uses in the past. The site of Beechfield in Salford, for example, which was used as water treatment site in the past contains Arsenic, Barium, Chromium and Copper all above the health limits defined by the WHO[2]. Indeed, an Environment Agency report in 2007 stated “Seven elements (Ce, Gd, Sb, Bi, Se, Mo and W) were found to be present at two or more UK industrial soils at concentrations greater than the generally reported range of concentrations in world soils. Of these, exceedances of the final five elements in particular (Sb, Bi, Se, Mo and W) are of note since they were spread across several industrial types”[3].
• Additionally, old sites such as the old gaswork sites [4] which are also very often found in residential areas show a different type of contamination since the soils are rich in hydrocarbons.
• While the metal contamination is a long lasting legacy and it slowly contaminates the water but largely remains at the site the hydrocarbon contamination generates air pollution as soon as the soil is mobilised. Due to the different nature of the contaminations the solutions and contingencies to be used in case of decontamination and redevelopment require a more holistic approach as soil, water and air contamination must be taken into account at once, including the time of residence and the spread with the overall winds in the areas of interest.
• In England for example, 15% of the total contaminated sites identified for remediation had petroleum hydrocarbons present within the soil[5]. Modelling [6] indicates that an acre of land contaminated with hydrocarbon with an initial concentration of total petroleum hydrocarbons of 12,320 µg/g could emit approximately 3 tons of aromatic per day during soil mobilisation reaching about 40m radius from the area of mobilisation and remaining active in the air for approximately 48hours, this would happen every time the soil is mobilised and left uncovered.

1.1.3         Urban soil contamination[7]

• The number of metal contaminated sites further grow when we look at metal contaminations in urban areas, indicating a much wider spread of such contaminants [8]. The Environmental Agency indicates that the range of concentrations of several trace metals (Cd, Cu, Hg, Ti, Zn) in urban soils is higher than in rural soils, indicating that sources of contamination might be ongoing for these metal2. Studies by the UK Centre for Ecology and Hydrology[9], carried out in 2008, indicate airborne contamination of at least Lead, Arsenic, Cadmium and Nickel. A citizen science project in the summer 2021[10] confirms these findings of higher copper, titanium and zinc in gardens of private individuals.

1.2   Soil decontamination solutions best practice

• Different practices of decontamination are commercially available up to date. There are two main approaches (physicochemicals and biological) to deal with non-metal contaminations. [11] Generally, the technical approach is to remove the highly contaminated soils to deal with them in dedicated plants with chemical methods while remediating the medium-contaminated soils on side using biological methods. The removal and mobilisation of soils being off site or on site, generating the liberation in the air of the pollutants as indicated in the previous section, while the on-site remediation without soil mobilisation is a much longer process, however it does not generate wider air pollution. On-site remediation with no soil mobilisation is limited to biological means.
• The remediation of metal-contaminated soil[12] follows a similar pattern and highly contaminated soils are generally removed from the site for chemical treatment and potential metal recovery, while micro-organisms and plants are used on site for a slower remediation. Recently scholars started developing techniques for the recovery of the metals from plants [13].

January 2023